Polyurethane foams have been conventionally used as water stopping sealing material in the fields of automobile, housing, building, civil engineering, and consumer electronics, etc. For example, in Patent Literature 1, in order to provide a water stopping polyurethane foam which can stably achieve high water stopping performance even having a low density, a water stopping polyurethane foam obtained by foaming polyurethane foam raw materials in combination of a dimer acid polyol and diphenylmethane diisocyanate (MDI) is proposed.
Further, in Patent Literature 2, in order to provide a polyurethane foam sealing material achieving both of a low density and low air permeability/high water stopping properties, formed from a polyurethane foam using a general-purpose PPG (polyoxypropylene glyceryl ether) based polyol and a MDI (diphenylmethane diisocyanate) based isocyanate, without using a special raw material system or a special additive to improve water stopping properties, a polyurethane foam sealing material having properties to achieve a water stopping pressure of 50 mm or more for a water stopping retaining time of 24 hours is provided by an appropriate blending of materials such as a general-purpose polyol and an isocyanate.